Beryllium (Be)
Alkaline earth metal · s-block · period 2 · group 2
Hard, steel-grey, lightweight metal.
Beryllium (symbol Be) is chemical element number 4, a alkaline earth metal in group 2, period 2 of the periodic table. Its standard atomic weight is 9.0122 and its electron configuration is [He] 2s2. At room temperature it is a solid. Transparent to X-rays, so it is used for windows in X-ray tubes.
Properties
| Atomic number | 4 |
|---|---|
| Atomic mass | 9.0122 |
| Category | Alkaline earth metal |
| Block | s-block |
| Group · Period | 2 · 2 |
| Electron configuration | [He] 2s2 |
| Electrons per shell | 2, 2 |
| State at 25 °C | solid |
| Melting point | 1560 K |
| Boiling point | 2742 K |
| Density | 1.85 g/cm³ |
| Electronegativity (Pauling) | 1.57 |
| Radioactive | No |
| Origin | primordial |
| Discovered | 1798 · Louis-Nicolas Vauquelin |
Key facts about Beryllium
- Transparent to X-rays, so it is used for windows in X-ray tubes.
- Extremely stiff for its weight — stiffer than steel.
- Its dust is highly toxic and causes a chronic lung disease.
- Found in the gemstones emerald and aquamarine (both are beryl).
What Beryllium is used for
Aerospace structures, X-ray windows, spring alloys with copper, nuclear reactor moderators.
Where it sits in the periodic table
Beryllium is in group 2, period 2, of the s-block. Its electron configuration [He] 2s2 means its outermost shell holds 2 electrons, which is what places it here and explains much of its chemistry. See Beryllium on the interactive table →
Beryllium — frequently asked questions
What is Beryllium used for?
Aerospace structures, X-ray windows, spring alloys with copper, nuclear reactor moderators.
Is Beryllium radioactive?
No. Beryllium has at least one stable isotope and is not radioactive.
What is the electron configuration of Beryllium?
Beryllium has the electron configuration [He] 2s2, which is 2, 2 electrons per shell.
What group and period is Beryllium in?
Beryllium is in group 2, period 2, in the s-block. Its outer shell holds 2 electrons.
Who discovered Beryllium?
Beryllium was discovered in 1798 by Louis-Nicolas Vauquelin.